The present invention relates to an image display device, and in particular to an image display device, such as a monitor, which can display color images, and which permits a user to adjust the color reproducibility.
A prior art method of adjusting the color reproducibility for an image display device is described with reference to FIG. 19.
FIG. 19 shows an example of control panel for adjusting the color reproducibility in the prior art image display device. In FIG. 19, reference numeral 101 denotes a red signal intensity setting means, 102 denotes a green signal intensity setting means, and 103 denotes a blue signal intensity setting means. In FIG. 19, the signal intensities of red, green and blue are adjusted using the red signal intensity setting means 101, the green signal intensity setting means 102 and the blue signal intensity setting means 103. For example, if the signal intensities of green and blue are reduced, the image displayed will generally be reddish.
In the image display device provided with the above-described adjusting means, it is only possible to adjust the signal intensities of red, green and blue, with respect to all the colors in the image, and it is not possible to finely adjust the colors according to the preference of the user. For instance, with the image display device provided with the above-described adjusting means, it is not possible to adjust only a specific color. Moreover, it is not possible to adjust the chroma of the color.
Japanese Patent Kokai Publication H05-48885 discloses a different method of adjusting the color image. According to the method disclosed in Japanese Patent Kokai Publication No. H05-48885, an image is displayed on an image display device, simulating an image outputted from a hard copy device. While observing the simulation image displayed on the image display device, the optimum parameters for the hard copy device are determined. The concept of the image adjustment for the hard copy device can be applied to an image display device.
FIG. 20 shows the configuration of a device using the image adjustment method disclosed in Japanese Patent Kokai Publication No. H05-48885. In FIG. 20, reference numeral 104 denotes a keyboard, 105 denotes a mouse, 106 denotes an input means, 107 denotes a controller, 108 denotes an input circuit, 109 denotes a memory, 110 denotes a CPU, 111 denotes an output circuit, 112 denotes an image display unit, 113 denotes an original image, 114 denotes a processed image, 115 denotes set parameters, and 116 denotes a hard copy device. The keyboard 104 and the mouse 105 are both an example of the input means 106. The controller 107 is formed of the input circuit 108 connected to the input means 106, the memory 109, the CPU 110, and the output circuit 111. The image display unit 112 is driven by the output circuit 111. The operation of the device using the image adjustment method of FIG. 20 will next be described.
The memory 109 stores a color conversion simulation program. The CPU 110 executes the program stored in the memory 109. First, it reads the image data used for the color conversion simulation. The image data having been read is displayed as the original image 113 on the image display unit 112. Next, the input means 106 is used to input the specific manner of processing specifying how the processing is to be performed. Then, the color conversion performed by the hard copy device 116 is simulated, on the image data having been read, in accordance with the designated manner of processing. The color converted, processed image 114 is displayed on the screen of the image display device 112, together with the original image 113. When the parameters for the color conversion can be changed step-wise, a plurality of the processed images which are obtained from the respective steps are displayed together, arranged in an array. By selecting that one of the processed images that is closest to the original image 113, the optimum parameters are determined. For determining a plurality of parameters, the above-mentioned operations are repeated, so that the parameters are determined in turn. The color conversion parameters thus determined are sent to the hard copy device.
In the device using the above-described image adjustment method, the color conversion is simulated in accordance specific manner of processing designated by the input means 106, and by selecting that one of the processed images which is optimum, the color conversion parameters can be determined. Accordingly, there ia a freedom in the adjustment depending on the type of the color conversion parameters that can be set. The freedom in the adjustment is greater than in the arrangement in which adjustment is made only on the signal intensities of red, green and blue. Moreover, it is easy for the user to set the parameters.
The above-described color adjustment method has a problem in that because simulation is performed by means of a CPU, if the accuracy of the simulation is low, the parameters that are determined are not necessarily optimum. Moreover, the load on the CPU which performs the simulation is heavy. Furthermore, because the simulation by means of the CPU is used, it is not suitable for a real-time processing of moving pictures due to the limitation in the processing speed.
When a plurality of processed images are displayed simultaneously, it is necessary to perform the simulation a number of times equal to the number of processed images displayed simultaneously, so that the problems of the load on the CPU and the processing speed are more serious. In addition, when a plurality of processed images are displayed simultaneously, the size of each of the displayed processed images is small, so that they may give different impression than the image outputted at full size, after the determination of the parameters.